1. Field of the Invention
The present invention relates generally to a grease applicator that is employed to apply grease to mechanical elements, such as a bearing, and in particular to a pneumatically operated grease applicator in which grease is supplied and driven to cover over the bearing by pneumatic force.
2. The Related Art
Industrial applications of bearings, for example heavy machinery, such as trucks and automobiles, require the bearings be uniformly coated with grease for lubrication purposes. Conventionally, the application of grease to bearings is done manually. In other words, workers apply grease to bearings by bear hands or hands with gloves. Since grease is a viscous substance, the application of grease to bearings is difficult, and often resulting in contamination of working site or the clothes and body of the worker by being unexpected or accidentally contacted by the workers' hands. Grease applicators are available in the market for addressing the drawback, and an example of the conventional grease applicator is shown in FIG. 1 of the attached drawings, and designated with reference numeral 1a. 
The conventional grease applicator, although effectively in applying grease to bearings, suffers the following drawbacks:
(A) The operation of the conventional grease applicator is based on the amount of grease fed in a grease receptacle 10a (see FIG. 1) of the applicator, and such an amount is limited due to the limited capacity of the receptacle. Once the grease is consumed up, the operation of applying grease must be interrupted and a presser 12a be removed for re-filling grease into the receptacle 10a. The pressure 12a is then mounted back to a retainer of the receptacle 10a after the replenishment of grease. Such repeated disengagement/engagement of the retainer and the presser 12a is quite likely to cause undesired contamination both inside and outside the receptacle 10a. Further, the requirement for frequent replenishment of grease makes it impossible to consecutively apply grease to a number of bearings.
(B) A tubular axle 111a formed on the retainer for replenishing grease must take the pressure of grease filling into the receptacle 10a and also needs to take the driving force acting thereon by the presser 12a during the application of grease. The tubular axle 111a is thus often in a pressed condition, which makes the tubular axle 111a fatigue and thus easily broken.
(C) Clearance or gap is present between the side wall of the receptacle 10a and the presser 12a, which causes severe leakage of grease out of the receptacle. Substantial replenishment of grease is required during the operation of the grease applicator. This means a great waste of grease.
(D) The operator must continuously apply a pressure to the presser with his or her hand. This often causes fatigue of the operator's hand and lowers the operation efficiency.
U.S. patent application Ser. No. 11/189,708, as illustrated in FIG. 2 of the attached drawings, which is also invented by the present inventor, provides a pneumatic grease applicator that overcomes the above discussed drawbacks of the conventional grease applicator. However, further improvement is desired to provide an even more advanced and efficient grease pneumatic applicator.